SQL FOREIGN KEY

SQL FOREIGN KEY

Introduction

In the realm of database management, SQL (Structured Query Language) reigns supreme as the standard language for interacting with relational databases. One of the fundamental concepts in SQL is the use of FOREIGN KEY constraints, which play a crucial role in maintaining the relationships between different tables in a database. This article delves into the intricacies of FOREIGN KEY constraints, explaining their purpose, usage, and significance in SQL databases.

Understanding FOREIGN KEY Constraints

Definition

A FOREIGN KEY in SQL is a column or a combination of columns that is used to establish a link between two tables. It is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table. The purpose of this constraint is to ensure referential integrity, meaning that relationships between tables are consistent and valid.

Basic Syntax

The basic syntax for cr

原文地址：https://blog.csdn.net/wjs2024/article/details/143842474

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